摘要
系统测定了迤纳厂矿床不同类型矿石、围岩和火山角砾岩、岩浆岩的稀土元素组成。研究表明,不同类型矿石均具REE总量高(726×10 6～4633×10 6)、铕正异常(1 68～5 16)、轻稀土强烈富集[(La/Yb)N=3 98～81 1]等特征,Y/Ho比值(24 4)小于球粒陨石中比值(28),与黑烟囱的比值接近。硅质白云岩及钠长石英斑岩、层状火山角砾岩的稀土特征(稀土总量低,铕负异常,轻重稀土分异不明显等)与矿石完全不同。成矿流体的稀土元素特征与现代大洋中脊热液相似,与裂谷初期的碱性火山岩稀土元素特征较为接近。结合矿床产出的大地构造背景,提出迤纳厂稀土铁铜矿床可能为昆阳裂谷初期碱性火山岩的喷发期间歇,来自地幔富稀土、富挥发份的成矿流体喷流 沉积成矿。
REE compositions of ores, wall rocks, alkaline volcanic rocks and albite quartz porphyry have been determined. Comparative studies of REE geochemical characteristics of these geologic bodies indicate that various ores and alkaline volcanicrockscontain abundant REE and Y (∑REE=65.9×10^(-6)-4633×10^(-6), Y=16.5×10^(-6)-290×10^(-6)), their chondrite-normalized patterns show a strong enrichment of LREE and positive Eu anomaly, in contrast with the dolomites which show a slight LREE enrichment and moderately negative Eu anomaly. The REE patterns of ores aresimilar to those of hydrothermal sedimentarycorein the East Pacific Rise, whereas the REE patternsof dolomites are like those of PAAS. In conjunction with the geological setting of the deposit, the primary ore-forming fluids might have higher REE and volatile elements derived from mantle degassing or alkaline volcanic magmas. The genesis of the Yinachang Fe-Cu-REE ore deposit might belong tovolcanic exhalation-hydrothermal sedimentary origin.
出处
《矿物学报》
CAS
CSCD
北大核心
2004年第3期301-308,共8页
Acta Mineralogica Sinica
基金
973项目(G1999042310)
中国大洋协会"十五"开发项目(DY105 01 04 02)
关键词
稀土元素
喷流沉积
铕正异常
富集
海底热液
元素地球化学
rare-earth elements
exhalation-hydrothermal
positive Eu anomaly
LREE enrichment
hydrothermal fluid
